Antenna apparatus

ABSTRACT

An antenna apparatus is disclosed. The antenna apparatus has a first antenna, a second antenna, and a third antenna which have different directivity directions each other and are switched for a desired directivity direction. The first antenna is disposed on a substrate which is in parallel therewith. The second antenna is disposed on one principal surface of the substrate which is nearly perpendicular thereto. The third antenna is disposed on the other principal surface of the substrate which is nearly perpendicular thereto.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention contains subject matter related to Japanese PatentApplication JP 2007-278099 filed in the Japanese Patent Office on Oct.25, 2007, the entire contents of which being incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an antenna apparatus, in particular, toan antenna apparatus on which a plurality of antennas are mounted andthat can switch from one directivity direction to another for radiocommunication.

2. Description of the Related Art

In radio systems such as wireless local area network (LAN), for highercommunication quality, a plurality of antennas are mounted and theirdirectivity directions are switched. By optimally controlling theplurality of antennas, deterioration of transmission quality, forexample, due to multipath fading can be suppressed. In addition, suchsystems can have resistance against disturbance from other radio devicesand narrow the range in which the systems disturb other radio devices.For example, Patent Document 1, disclosed as Japanese Patent ApplicationLaid-Open No. 2007-251677, describes a radio communication apparatus onwhich a plurality of antennas having different directivities aremounted.

FIG. 1 shows an exemplary structure of an antenna apparatus having aplurality of antennas as a related art reference. The antenna apparatushas a substrate 101 composed of a wireless module and so forth, a radiocircuit section 102 disposed on the substrate 101, six antennas 103 a,103 b, 103 c, 103 d, 103 e, and 103 f (hereinafter, they are generallydesignated by antennas 103 unless otherwise specified). This antennaapparatus is used in such a manner that the principal surfaces lay down.

As shown in FIG. 1, the six antennas 103 are disposed in such a mannerthat they form a circumference of a circle on a horizontal surface ofone principal surface of the substrate board 101. Since the antennas 103are nearly equiangularly disposed such that they divide thecircumference of the circuit into six sectors, the antennas 103 can havedirectivities of different directions from each other.

In the radio communication using such an antenna apparatus, an optimumantenna 103 is selected from the plurality of antennas 103 correspondingto the exiting communication environment. Through the selected antenna103, radio communication is performed. To reduce the influence ofoverlapping of adjacent antennas 103, it is necessary to isolate theselected antenna 103 from the adjacent antennas 103 for a predeterminedamount. Thus, the spaces of the antennas 103 are secured correspondingto the communication frequencies of the radio system.

However, if the antennas 103 are disposed on the same plane as shown inFIG. 1, it is necessary to secure the spaces of the antennas 103 fortheir isolation. Thus, the overall structure of the antenna apparatusbecomes large. This is a cause that prevents a product having theantenna apparatus from being downsized.

When this antenna apparatus is mounted on arectangular-parallelepiped-shaped electronic device, if it is designedto lay down where the largest side of the six sides of the rectangularparallelepiped body is the bottom of the electronic device, it seemsthat the plurality of antennas 103 can be relatively easily mounted. Incontrast, if the electronic device is designed to stand upright wherethe smallest side of the six sides of the rectangular parallelepipedbody is the bottom of the electronic device, since the bottom area isnot large, it becomes difficult to dispose the antennas 103. Thus, theshape of the product is restricted.

In addition, in the radio system that switches from one directivity toanother of the plurality of antennas 103, as the number of antennas 103is increased, the performance can be improved. However, if the number ofantennas 103 is increased, the circumference of the circle in which theantennas 103 are disposed is increased. Thus, the space in which theantennas 103 are disposed is increased. As a result, since there is atradeoff between the performance of the antennas and the area in whichthey are disposed, an antenna apparatus that allows the plurality ofantennas 103 can be disposed in a saved space is being desired.

To solve such a problem, Patent Document 2, disclosed as Japanese PatentNo. 3456507, describes a selector antenna that has a plurality ofantenna elements disposed vertically, not horizontally and that allowsthe outer diameter (bottom area) of the sector antenna to be decreasedwithout changing of directivity characteristics.

SUMMARY OF THE INVENTION

However, in the related art reference as Patent Document 2 above, sincethe plurality of antenna elements are disposed at different heights, thevertical length of the sector antenna increases corresponding to thenumber of antenna elements disposed vertically. Thus, the overall sizeof the sector antenna is not decreased. In addition, a problem of whichthe solid arrangement of the antenna elements becomes complicatedarises.

In view of the foregoing, it would be desirable to provide an antennaapparatus that secures isolation between adjacent any two of theplurality of antennas and that can be downsized in a simple structure.

According to an embodiment of the present invention, there is providedan antenna apparatus having a first antenna, a second antenna, and athird antenna which have different directivity directions each other andwhich are switched for a desired directivity direction. The firstantenna is disposed on a substrate which is in parallel therewith. Thesecond antenna is disposed on one principal surface of the substratewhich is nearly perpendicular thereto. The third antenna is disposed onthe other principal surface of the substrate which is nearlyperpendicular thereto.

According to an embodiment of the present invention, by combining gainpatterns of adjacent two antennas of the first antenna, the secondantenna, and the third antenna, it is preferred that a fourth antennapattern be obtained in a direction different from a first antenna gainpattern obtained from the first antenna, a second antenna gain patternobtained from the second antenna, and a third antenna gain patternobtained from the third antenna.

According to an embodiment of the present invention, it is preferredthat a connector socket be mounted on the substrate, pin headers bemounted on the second antenna and the third antenna, and by fitting thepin headers to the connector socket, the second antenna and the thirdantenna be nearly perpendicularly connected to the substrate.

According to an embodiment of the present invention, it is preferredthat the pin header have at least three pins and the at least three pinsbe fit to the connector socket.

According to an embodiment of the present invention, the first antennais disposed on the substrate which is in parallel therewith and thesecond antenna and the third antenna are disposed on the substrate whichis nearly perpendicular thereto. Thus, while isolation of the firstantenna, the second antenna, and the third antenna is kept, they can bedisposed in a saved space.

According to embodiments of the present invention, while isolation of aplurality of antennas is secured, they can be disposed in a simplestructure and in a saved space. As a result, downsizing of the antennaapparatus can be accomplished.

These and other objects, features and advantages of the presentinvention will become more apparent in light of the following detaileddescription of a best mode embodiment thereof, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an exemplary structure of an antennaapparatus having a plurality of antennas as a related art reference;

FIG. 2 is a schematic diagram showing the overall structure of awireless LAN system to which an antenna apparatus according to a firstembodiment of the present invention is applicable;

FIG. 3 is a perspective view showing an exemplary structure of anantenna apparatus of a radio base station according to the firstembodiment of the present invention;

FIG. 4 is an enlarged view showing an example of a connection portion ofa substrate and antennas of the antenna apparatus according to the firstembodiment of the present invention;

FIG. 5A and FIG. 5B are enlarged views showing a connector socket and apin header of the antenna apparatus according to the first embodiment ofthe present invention;

FIG. 6A, FIG. 6B, and FIG. 6C are schematic diagrams describingconnections of the substrate and the pin header of the antenna apparatusaccording to the first embodiment of the present invention;

FIG. 7 is a schematic diagram showing a structure of a radiocommunication system composed of a radio base station and a radioterminal according to the first embodiment of the present invention;

FIG. 8 is a block diagram showing an overall structure of the antennaapparatus of the radio base station according to the first embodiment ofthe present invention;

FIG. 9 is a schematic diagram showing an exemplary structure of anantenna apparatus for a radio base station and a radio terminalaccording to a second embodiment of the present invention;

FIG. 10 is a block diagram showing an overall structure of the radioterminal according to the second embodiment of the present invention;and

FIG. 11 is a schematic diagram showing a structure of an antennaswitching and combining device of the radio terminal according to thesecond embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, with reference to the accompanying drawings, embodiments of thepresent invention will be described.

First Embodiment

An antenna apparatus according to a first embodiment of the presentinvention can be applied to a location-free visual-audio system that hasplace shift function, this system being, for example, calledLocationFree (registered trademark of Sony Corporation) with which theuser can watch and listen to content such as television programswherever he or she is. The minimum structural components of the placeshift visual-audio system are a base station that is a contenttransmitting apparatus and a receiving apparatus (also referred to as alocation free player or a client) that provide picture and sound to theuser.

First, with reference to FIG. 2, the structure of a content transmittingand receiving system using wireless LAN will be briefly described.Connected to a base station 1 that is the content transmitting apparatusis a television antenna 2. Thus, the base station 1 can receivetelevision broadcast content (eg, analog television broadcast content).In addition, the base station 1 may receive television broadcast contentof satellite digital broadcast, terrestrial digital broadcast, cabletelevision, Internet television, and so forth.

Moreover, connected to the base station 1 is a disc player 5 such as adigital versatile disc (DVD) player or a Blu-ray Disc (BD) player. Thedisc player 5 can output a standard definition (SD) picture or a highdefinition (HD) picture recorded on a disc to the base station 1according to an external control command.

Channel switching of broadcast programs that the base station 1transmits and the operation of the disc player 5 can be remotelycontrolled by the receiving apparatus (location free player or client).For example, an AV mouse 4 is connected to the base station 1 and theoperation of the disc player 5 is remotely controlled through the AVmouse 4 by the receiving apparatus.

The base station 1 has an antenna apparatus 6. The antenna apparatus 6of the base station 1 and an antenna apparatus 10 of a television box 7form wireless LAN. Broadcast content received by the base station 1 andcompression-encoded data of reproduced picture and so forth of the discplayer 5 are transmitted to the television box 7 through the wirelessLAN. Data are packetized and transmitted. The wireless LAN systems arebased on three IEEE 802.11b/g/a standards.

In the antenna apparatus 6 and 10, a sector antenna is composed of aplurality of directivity antennas. For a directivity of a desireddirection, one of these directivity antennas is selected. The structureof the antenna apparatus 6 and 10 will be described later.

Connected to the wireless LAN is the television box 7, which is acontent receiving apparatus. The television box 7 decodes data ofbroadcast content received through the wireless LAN and outputs thedecoded data as an analog video audio signal. The analog video audiosignal is supplied to a video input terminal of a display 8 (eg, atelevision receiver). With the display 8, the user can watch and listento a television broadcast program transmitted from the base station 1.

In addition, the television box 7 decodes reproduced picture data of thedisc player 5 received through the wireless LAN and outputs the decodeddata as a digital video audio signal. The digital video audio signal issupplied to the input terminal of the display 8. With the display 8, theuser can watch and listen to an HD picture and so forth transmitted fromthe base station 1.

A remote control commander 9 can remotely control the television box 7.

With the display 8, the user can watch and listen to broadcast contenttransmitted from the base station 1. In addition, with the function ofthe television box 7, the display 8, and the commander 9, data can beset for the base station 1 and the disc player 5 and so forth connectedthereto and they can be remotely controlled.

When the television antenna 2 and the disc player 5 are to the basestation 1 in such a manner, the user can watch and listen to a livetelevision broadcast program or a reproduced picture of the disc player5 through the wireless LAN in any room of the house. In the followingdescription, in the wireless LAN system, a side such as the base station1 that transmits data of reproduced picture and so forth is sometimesreferred to as a radio base station. On the other hand, a side such asthe television box 7 that receives data of reproduced picture and soforth is sometimes referred to as a radio terminal.

Next, with reference to FIG. 3, an exemplary structure of the antennaapparatus 6 disposed on the base station 1 will be described. FIG. 3 isa perspective view showing an exemplary structure of the antennaapparatus 6. The antenna apparatus 6 is mainly composed of a substrate11, a circuit section 12, antennas 60 b and 60 e as a first antennagroup, antennas 60 a and 60 f as a second antenna group, and antennas 60c and 60 d as a third antenna group. In the following description, theantennas 60 a, 60 b, 60 c, 60 d, 60 e, and 60 f are generallyrepresented by antennas 60, unless otherwise specified. The antennaapparatus is used in the state that the principal surfaces of thesubstrate 11 stand upright.

The substrate 11 is composed, for example, of a wireless module. Thesubstrate 11 is a multi-layered substrate composed, for example, of fourlayers. The inner two layers are used as a power supply layer and aground layer. The outer two layers are used as a component mountinglayer and a circuit wiring layer. These layers are insulated by bondingagent or the like. These layer are connected, for example, bythrough-holes formed in the substrate 11.

The circuit section 12 is disposed, for example, nearly at a centerportion of one principal surface on the substrate 11. The circuitsection 12 includes various types of circuits that select an optimum onefrom the plurality of antennas 60 for radio communication. A specificcircuit structure of the circuit section 12 will be described later.

The antennas 60 are planar printed antennas as wiring patterns, forexample, formed on the front surface of the substrate. The antennas 60are, for example, dipole antennas and can handle radio signals of 2.4GHz and 5 GHz. In the first embodiment, an example of which six antennas60 are disposed is described. However, it is appreciated that the numberof antennas 60 is not limited to any specific number.

As shown in FIG. 3, the antennas 60 b and 60 e as the first antennagroup are disposed on both ends of principal surfaces of the substrate11 in parallel with the substrate 11. The antennas 60 b and 60 e arenearly symmetrical with respect to the circuit section 12.

The antennas 60 a, 60 c, 60 d, and 60 f are disposed nearlyperpendicular to the substrate 11. The antennas 60 a and 60 f as thesecond antenna group are disposed on one principal surface of thesubstrate 11. The antennas 60 c and 60 d as the third antenna group aredisposed on the other principal surface of the substrate 11. Theantennas 60 a and 60 c are disposed on the principal surfaces of thesubstrate 11 between the circuit section 12 and the antenna 60 b,whereas the antennas 60 d and 60 f are disposed on the principalsurfaces of the substrate 11 between the circuit section 12 and theantenna 60 e.

Thus, since the second antenna group (antennas 60 a and 60 f) and thethird antenna group (antennas 60 c and 60 d) are adjacent to andperpendicular to the first antenna group (antennas 60 b and 60 e),respectively, the plurality of antennas can be disposed in a savedspace. As a result, the horizontal surface (the horizontal surface ofwhich the principal surfaces of the substrate 11 stand upright) can besmall. Thus, downsizing of the antenna apparatus 6 can be accomplished.

These antennas 60 have directivity directions that are different fromeach other. The directivity direction of each of the antennas 60 is adirection in which a radio signal is transmitted by the radio basestation and received by the antenna apparatus 6.

In addition, these antennas 60 can have sufficient isolationtherebetween. Since the antenna 60 b is perpendicular to each of theantennas 60 a and 60 c, even if they are disposed close to each other,they can have sufficient isolation therebetween. Likewise, since theantenna 60 e is perpendicular to each of the antennas 60 d and 60 f,even if they are disposed close to each other, they can have sufficientisolation therebetween.

Although the antennas 60 a and 60 c are disposed close to each other,they are interposed through the substrate 11, the ground layer of thesubstrate 11 provides a shielding effect against electromagnetic waves,resulting in providing sufficient isolation. Likewise, since theantennas 60 d and 60 f are interposed through the substrate 11, they canhave sufficient isolation therebetween.

Since antennas 60 a and 60 f are spaced to some extent, they can haveisolation therebetween. Likewise, since the antennas 60 c and 60 d arespaced to some extent, they can have isolation therebetween.

The antennas 60 a, 60 c, 60 d, and 60 f are disposed nearlyperpendicular to the substrate 11 using connector sockets 13 and pinheaders 15. Next, with reference to FIG. 4 to FIG. 6, an example ofwhich the antennas 60 are disposed perpendicular to the substrate 11will be described.

FIG. 4 is an enlarged view showing an example of a connection portion ofthe substrate 11 and the antenna 60 a. By connecting the connectorsocket 13 mounted on the substrate 11 and the pin header 15 mounted onthe antenna 60 a, the antenna 60 a stands upright perpendicular to thesubstrate 11. By fitting holes 14 formed on the connector socket 13facing the pin header 15 to pins 17 formed on the pin header 15 facingthe connector socket 13, which is nearly rectangular parallelepiped (inFIG. 4, since the pins 17 have been inserted into the fitting holes 14,the pins 17 are not shown), the connector socket 13 and the pin header15 are connected.

FIG. 5A is an enlarged view showing an example of the connector socket13. The connector socket 13 may be a general-purpose member. As shown inFIG. 5A, a plurality of fitting holes 14 are formed in the connectorsocket 13, facing the pin header 15. The pins 17 extruding from the pinheader 15 are fit to the fitting holes 14. The number of fitting holes14 is not limited as long as it is larger than the number of pins 17that extrude from the pin header 15. FIG. 5A shows an example of whichthe number of fitting holes 14 is 12. In this example, of 12 fittingholes 14, fitting holes 14 a, 14 b, 14 c, and 14 d are used.

FIG. 5B is an enlarged view showing an example of the pin header 15.Like the connector socket 13, the pin header 15 may be a general-purposemember. Formed on one surface of the pin header 15 are pins 17 a, 17 b,17 c, and 17 d (hereinafter, they are generally designated by pins 17unless otherwise specified). The pins 17 are fit to the fitting holes 14of the connector socket 13.

Formed on the pin header 15 are pins 16 a, 16 b, 16 c, and 16 d(hereinafter, they are generally designated by pins 16 unless otherwisespecified) on a surface adjacent to the surface on which the pins 16 a,16 b, 16 c, and 16 d are formed. The pins 16 are those that are fit andconnected to through-holes of the antenna 60 a.

The pins 16 and the pins 17 each are composed, for example, of one powersupply terminal, two ground connection terminals, and one reinforcementpin. Although it is sufficient to form a total of two pins 16 connectedto the antenna 60 a, one power supply terminal and one ground terminal,if they are fit to the through-holes of the antenna 60, their fittingstrength is not high. Thus, it is difficult to allow the pins 16 tostably hold the antenna 60 a against the substrate 11 in such a mannerthat the antenna 60 a is disposed perpendicular to the substrate 11.Consequently, it is preferred that the numbers of pins 16 and pins 17 beat least three each.

FIG. 6A shows the antenna 60 a to which the pin header 15 has not yetbeen mounted. Formed on the antenna 60 a are through-holes 61 a, 61 b,61 c, and 61 d (hereinafter, they are generally designated bythrough-holes 61, unless otherwise specified). The number ofthrough-holes 61 corresponds to the number of pins 16 formed on the pinheader 15. In this example, four through-holes 61 are formed. The widthof adjacent through-holes 61 corresponds to the width of adjacent pins16 formed in the pin header 15.

FIG. 6B and FIG. 6C show the antenna 60 a on which the pin header 15 hasbeen mounted. FIG. 6B is a schematic diagram showing the antenna 60 aviewed from the pin header 15 mounted thereon. FIG. 6C is a schematicdiagram showing the antenna 60 a viewed from the pins 16 fit to thethrough-holes 61. As shown in FIG. 6B and FIG. 6C, by inserting the pins16 of the pin header 15 into the through-holes 61, the antenna 60 a andthe pin header 15 are connected. The through-holes 61 and the pins 16are individually soldered such that the antenna 60 a and the pins 16 aremore securely connected. Thus, by fitting the pins 16 of the pin header15 to the fitting holes 14 of the connector socket 13, the antenna 60 ais connected to the substrate 11 through the pin header 15 and theconnector socket 13.

The antennas 60 c, 60 d, and 60 f are connected to the substrate 11 inthe same manner as that of the antenna 60 a.

Like the antennas 60 b and 60 e disposed on the substrate 11, when theantenna 60 is directly connected to a power supply line on the substrate11, matching is performed taking into account of characteristicimpedance (eg, 50 ohms) of the antenna 60.

In contrast, like the antennas 60 a, 60 c, 60 d, and 60 f, when theantenna 60 a is connected to a power supply line through the connectorsocket 13 and the pin header 15 on the substrate 11, matching isperformed taking into account of the specific impedance of the antennas60 and impedances of the connector socket 13 and the pin header 15.

With general-purpose connector socket 13 and pin header 15, the antenna60 a can be disposed perpendicular to the substrate 11 at low cost andeasily.

FIG. 7 is a schematic diagram showing a structure of a radiocommunication system of a radio base station 21 and a radio terminal 22.As shown in FIG. 7, the antenna 60 a has an antenna gain pattern 61 a asits characteristic. Likewise, the antennas 60 b, 60 c, 60 d, 60 e, and60 f have antenna gain patterns 61 b, 61 c, 61 d, 61 e, and 61 f astheir characteristics, respectively. Thus, since the antennas 60 haveantenna gain patterns that differ in their directions, directivitiesthat nearly cover 360° can be obtained.

When data are transmitted from the radio base station 21, an antenna 60having a higher radio condition than the others of the plurality ofantennas 60 is selected by the sector antenna system. Likewise, whendata are received from the radio terminal 22, an antenna 60 having ahigher radio condition than the other of the plurality of antennas 60 isselected.

FIG. 8 is a block diagram showing an overall structure of an antennaapparatus of the radio base station 21 according to the first embodimentof the present invention. The antennas 60 of the radio base station 21are switched by an antenna switching circuit 31. Through the selectedantenna 60, a high frequency signal supplied from a transmission circuitsection 33 through the antenna switching circuit 31 is transmitted as aradio signal. On the other hand, through the selected antenna 60, a highfrequency signal of a radio signal received from the radio terminal 22is supplied to a reception circuit section 34 via the antenna switchingcircuit 31.

The antenna switching circuit 31 switches between ON/OFF states of theantennas 60 according to an antenna switching signal supplied from acontrolling section 32.

Supplied from the controlling section 32 to the transmission circuitsection 33 is a transmission signal. The transmission circuit section 33has a high frequency amplifying circuit, a frequency converting circuit,and so forth that convert the transmission signal into a high frequencysignal and transmits the high frequency signal. The high frequencysignal is transmitted from the selected antenna 60 through the antennaswitching circuit 31.

Supplied to the reception circuit section 34 is a radio signal receivedby the antenna 60. The reception circuit section 34 has a high frequencyamplifying circuit, a frequency converting circuit, an AGC circuit, andso forth receive a high frequency signal and convert it into a receptionsignal. The reception signal is supplied to an interface 36 through thecontrolling section 32.

The controlling section 32 is composed, for example, of a digital signalprocessor (DSP) that performs a calculating process. The controllingsection 32 performs diversity control, which is a process of setting adirectivity direction of an antenna 60 for the highest communicationquality in radio communication with the radio terminal 22. In thisprocess, by generating an antenna switching signal on the basis ofinformation such as packet error rates of the antennas 60 and supplyingthe antenna switching signal to the antenna switching circuit 31, adirectivity direction is selected. In addition, the controlling section32 performs a process of transmitting a reference signal through theselected antenna 60 and a process of detecting a response signalcorresponding to the reference signal. The reference signal is used todetermine quality of communication between the radio base station 21 andthe radio terminal 22. The reference signal is for example a existingcommunication quality determination signal or a network control signaldefined in the relevant radio communication standard.

In addition, the controlling section 32 frame-segments transmission datasupplied from the interface 36 and generates address information thatrepresents a transmission recipient and a transmission sender and headerinformation composed of various types of control information and soforth. The controlling section 32 generates a predeterminedframe-formatted transmission signal from the generated headerinformation and frame-segmented transmission data and supplies thegenerated transmission signal to the transmission circuit section 33.

When the reception signal is supplied from the reception circuit section34 to the controlling section 32, it selects a self-addressed framebased on the header information and supplies a data signal contained inthe selected frame as reception data to the interface 36.

Connected to the controlling section 32 is a memory 35. The memory 35 iscomposed of a non-volatile electrically erasable and programmable ROM(EEPROM). The memory 35 stores a program that causes the controllingsection 32 to execute a control operation, information necessary forradio communication, and information such as a packet error rates thatrepresent radio conditions of individual antennas.

Next, the radio communication operation of the radio base station 21will be described. When the operation of the radio base station 21 isstarted, the controlling section 32 selects an antenna having a highersuccess rate based on information such as packet error rates ofindividual antennas 60, for example, stored in the memory 35 andsupplies an antenna switching signal to the antenna switching circuit31. The antenna switching circuit 31 switches among the antennas 60according to the supplied antenna switching signal. Through the selectedantenna 60, the reference signal is transmitted.

Thereafter, the controlling section 32 determines whether or not throughthe selected antenna 60 a response signal corresponding to the referencesignal has been received from the radio terminal 22. When the responsesignal has been received from the radio terminal 22, the controllingsection 32 correlates the radio base station 21 with the radio terminal22 on a one-to-one basis (this operation is referred to as pairing).Pairing means that identification information of the substrate 11 andthat of the radio base station 21 are exchanged. As identificationinformation, ID such as a message authentication code (MAC) address, anaddress generated by an MAC address, or the like is used. If thecontrolling section 32 has not received the response signal from theradio terminal 22, the controlling section 32 selects another antenna 60different from that through which the reference signal has beentransmitted, transmits the reference signal to the radio terminal 22through the newly selected antenna 60, and performs pairing with theradio terminal 22.

The controlling section 32 establishes a link with the radio terminal 22using the antenna 60 through which pairing has been successfullyperformed. Through the established link, radio communication is madebetween the radio base station 21 and the radio terminal 22. If thecommunication condition of the selected antenna is deteriorating, thecontrolling section 32 switches from the current antenna 60 to anotherantenna 60 and performs radio communication through the newly selectedantenna.

Next, with reference to FIG. 3 to FIG. 8, the structure and operation ofthe antenna apparatus 6 of the radio base station 21 have beendescribed. The antenna apparatus 6 of the radio base station 21 can beapplied to the antenna apparatus 10 of the radio terminal 22. In thiscase, the radio terminal 22 selects an antenna having a higher level ofa radio signal transmitted from the radio base station 21 from theplurality of antennas, transmits a response signal corresponding to thereference signal supplied from the radio terminal 22 thereto, andestablishes a link with the radio base station 21. The radio terminal 22performs radio communication with the radio base station 21 through theestablished link. If the communication condition of the selected antennais deteriorating, the radio terminal 22 selects another antennadifferent from the antenna that is deteriorating.

As described above, according to the first embodiment, the antenna 60 bis disposed perpendicular to the antennas 60 a and 60 c. Likewise, theantenna 60 e is disposed perpendicular to the antennas 60 d and 60 f. Asa result, the plurality of antennas 60 can be disposed in a saved space.Thus, downsizing of the antenna apparatus 6 can be accomplished. Inaddition, the number of antennas 60 can be increased without necessityof increasing the size of the antenna apparatus 6. In addition, with theconnector sockets 13 and pin headers 15 as general-purpose members, theantennas 60 can be disposed nearly perpendicular to the substrate 11.Since the structure of the connection portions are not complicated, theantennas 60 and the substrate 11 can be connected at low cost andeasily.

Second Embodiment

A second embodiment of the present invention is an antenna apparatushaving a plurality of antennas disposed perpendicular to each other. Inthe antenna apparatus according to the second embodiment, by combininggain patterns of individual antennas, variation of antenna gain patternsis increased. Like the first embodiment, the antenna apparatus accordingto the second embodiment can be used for the radio base station 21 andthe radio terminal 22.

Next, with reference to FIG. 9, the structure of the antenna apparatusaccording to the second embodiment will be described. FIG. 9 is aschematic diagram showing the structure of the antenna apparatusaccording to the second embodiment viewed from the top of the antennaapparatus in the case that principal surfaces of a substrate 11 standupright. In the second embodiment, it is assumed that the antennaapparatus has four antennas 70 a, 70 b, 70 c, and 70 d (hereinafter,they are generally designated as antennas 70 unless otherwisespecified).

The antennas 70 b and 70 d are disposed in parallel with the substrate11. The antenna 70 b is disposed at one end of the principal surfaces ofthe substrate 11. The antenna 70 d is disposed on the other end of theprincipal surfaces of the substrate 11.

The antenna 70 a is disposed nearly perpendicular to one principalsurface of the substrate 11. On the other hand, the antenna 70 c isdisposed nearly perpendicular to the other principal surface of thesubstrate 11. Since the adjacent antennas 70 are disposed perpendicularthereto, they can be disposed in a saved space while their isolation iskept. Like the first embodiment, since the antennas 70 a and 70 c aredisposed through the substrate 11, their isolation is kept with a groundlayer of the substrate 11. Since the antennas 70 a and 70 c areconnected to the substrate 11 such that the antennas 70 a and 70 c areperpendicular to the substrate 11 in the same manner as the firstembodiment, the description will be omitted.

As shown in FIG. 9, the antenna 70 a has an antenna gain pattern 71 a asits characteristic. Likewise, the antenna 70 b has an antenna gainpattern 71 b as its characteristic. The antenna 70 c has an antenna gainpattern 71 c as its characteristic. The antenna 70 d has an antenna gainpattern 71 d as its characteristic.

In the second embodiment, by combining the antenna gain patterns 71 ofadjacent antennas 70, the variation of the antenna gain patterns 71 canbe increased. Specifically, by combining the antenna gain patterns 71 aand 71 b of the antennas 70 a and 70 b, an antenna gain pattern 71 e canbe obtained in a direction that is different from those of the antennagain patterns 71 a and 71 b. Likewise, by combining the antenna gainpatterns 71 b and 71 c of the antennas 70 b and 70 c, an antenna gainpattern 71 f can be obtained in a direction that is different from thoseof the antenna gain patterns 71 b and 71 c. Likewise, by combining theantenna gain patterns 71 c and 71 d of the antennas 70 c and 70 d, anantenna gain pattern 71 g can be obtained in a direction that isdifferent from those of the antenna gain patterns 71 c and 71 d.Likewise, by combining the antenna gain patterns 71 d and 71 a of theantennas 70 d and 70 a, an antenna gain pattern 71 h can be obtained ina direction that is different from those of the antenna gain patterns 71d and 71 a.

Thus, in the second embodiment, in addition to the four antenna gainpatterns 71 of the four antennas, by combining antenna gain patterns 71of adjacent antennas 70, four more antenna gain patterns 71 can beobtained. Consequently, when it is necessary to dispose eight antennasin the antenna apparatus, by disposing the antennas 70 and combining theantenna gain patterns as shown in FIG. 9, the number of antennas to bedisposed can be decreased and more downsizing of the antenna apparatuscan be accomplished.

FIG. 10 is a block diagram showing an overall structure of the radioterminal 22 according to the second embodiment of the present invention.The antennas 70 of the radio terminal 22 are switched by an antennaswitching and combining device 42 through a variable phase shifter 41and antenna gain patterns 71 are combined. A high frequency signal isreceived from the radio base station 21 based on the combined antennagain pattern 71. The received high frequency signal is supplied to areception circuit section 45 through the variable phase shifter 41 andthe antenna switching and combining device 42. On the other hand, a highfrequency signal supplied from a transmission circuit section 44 throughthe antenna switching and combining device 42 is transmitted as a radiosignal.

The variable phase shifter 41 adjusts the phases of the selected twoadjacent antennas 70 according to a variable phase shifter controlsignal supplied from a controlling section 43. As a result, by combiningthe antenna gain patterns 71 of the antennas 70, a new antenna gainpattern 71 can be obtained between the adjacent antennas 70.

The antenna switching and combining device 42 switches between ON/OFFstates of the antennas 70 and selects one antenna 70 according to theantenna switching signal supplied from the controlling section 43 andcombines antenna gain patterns 71 of the antennas 70. The antenna gainpatterns 71 of the adjacent antennas 70 are combined based on combiningpatterns corresponding to the selected antennas.

When the antenna 70 a has been selected by the antenna switching andcombining device 42, only the antenna gain pattern 71 a of the antenna70 a is obtained. When the adjacent antennas 70 a and 70 b have beenselected, the antenna gain patterns 71 a and 71 b of the adjacentantennas 70 a and 70 b are combined and the antenna gain pattern 71 e isobtained. By combining antenna gain patterns 71 of adjacent antennas 70in such a manner, eight antenna gain patterns can be obtained from fourantennas 70.

Supplied from the controlling section 43 to the transmission circuitsection 44 is a transmission signal. The transmission circuit section 44has a high frequency amplifying circuit, a frequency converting circuit,and so forth that convert the transmission signal into a high frequencysignal and transmit it. The high frequency signal is transmitted fromthe selected antenna 70 as the transmission antenna through the antennaswitching and combining device 42.

Supplied to the reception circuit section 45 is a radio signal receivedthrough the antenna 70. The reception circuit section 45 has a highfrequency amplifying circuit, a frequency converting circuit, an AGCcircuit, and so forth that receive the radio signal as a high frequencysignal and convert it to a reception signal. The reception signal issupplied to an interface 47 through the controlling section 43.

The controlling section 43 is composed, for example, of a digital signalprocessor that can perform a calculating process. The controllingsection 43 performs diversity control, which is a process of setting adirectivity direction of an antenna 70 for the highest communicationquality in radio communication with the radio base station 21. If thecontrolling section 43 has determined that the antenna gain pattern 71 aof the antenna 70 a be optimum, the controlling section 43 generates anantenna switching signal corresponding to the antenna 70 a and suppliesthis antenna switching signal to the antenna switching and combiningdevice 42 to select the directivity direction. If the controllingsection 43 has determined that the antenna gain pattern 71 e of whichthe antenna gain pattern 71 a of the antenna 70 a and the antenna gainpattern 71 b of the antenna 70 b are combined be optimum, thecontrolling section 43 generates an antenna switching signalcorresponding to the antennas 70 a and 70 b and supplies this antennaswitching signal to the antenna switching and combining device 42. Inaddition, the controlling section 43 supplies a variable phase shiftercontrol signal corresponding to the antenna gain patterns of theantennas 70 to be combined to the variable phase shifter 41 based onphase shifter adjustment patterns corresponding to the antennas 70stored in a memory 46.

In addition, when the reception signal is supplied from the transmissioncircuit section 44 to the controlling section 43, it selects aself-addressed frame using header information and supplies a data signalcontained in the selected frame as reception data to the interface 47.

In addition, the controlling section 43 frame-segments transmission datasupplied from the interface 47 and generates address information thatrepresents a transmission recipient and a transmission sensor and headerinformation composed of various types of control information. Thecontrolling section 43 generates a predetermined frame-formattedtransmission signal using the generated header information andframe-segmented transmission data and supplies the generatedtransmission signal to the transmission circuit section 44. When thecommunication state of the reference signal received from the radio basestation 21 is good, the controlling section 43 supplies a responsesignal corresponding to the reference signal to the transmission circuitsection 44.

Connected to the controlling section 43 is the memory 46. The memory 46is composed of a non-volatile EEPROM. The memory 46 stores a programthat causes the controlling section 43 to execute a control operation,information necessary for radio communication, and information such asdata of a variable phase shifter control signal. Data of the variablephase shifter control signal contain phase adjustment patterns of whichantenna gain patterns 71 of antennas 70 are combined such that bycombining antenna gain patterns 71 of adjacent antennas 70, an antennagain pattern 71 of any direction can be obtained. When the antenna gainpatterns 71 a and 71 b of the antennas 70 a and 70 b are combined, aphase adjustment pattern of which antenna gain patterns of antennas 70are combined is used as a variable phase shifter control signal.

Next, with reference to FIG. 11, the structure of the antenna switchingand combining device 42 will be described in detail. Although FIG. 11shows the structure in the case that a radio signal is received with anantenna 70, the same structure can be applied to the case that a radiosignal is received.

As shown in FIG. 11, the antenna switching and combining device 42 iscomposed of a switching section 42 a and an adding device 42 b. Theantenna switching and combining device 42 has switches SW1, SW2, SW3,and SW4 that are connected to the individual antennas 70. These switchesSWs are turned ON/OFF according to an antenna switching signal suppliedfrom the controlling section 43. For example, when the antenna 70 a isselected, only SW1 is turned ON. Likewise, when the antenna 70 b isselected, only SW2 is turned ON. When the antenna 70 c is selected, onlySW3 is turned ON. When the antenna 70 d is selected, only SW4 is turnedON. A reception signal received by the selected antenna 70 is suppliedto the reception circuit section 45 through the adding device 42 b.

On the other hand, when adjacent two antennas 70 are selected, switchescorresponding to the adjacent two antennas 70 are turned ON. Forexample, when the antennas 70 a and 70 b are selected, SW1 and SW2 areturned ON. Likewise, when the antennas 70 b and 70 c are selected, SW2and SW3 are turned ON. When the antennas 70 c and 70 d are selected, SW3and SW4 are turned ON. When the antennas 70 d and 70 a are selected, SW4and SW1 are turned ON. The reception signals received by the selectedantennas 70 are phase-adjusted by the variable phase shifter 41 and thenthey are added based on preset combining patterns and then supplied tothe reception circuit section 45.

Next, the radio communication operation of the radio terminal 22 will bedescribed. When the operation of the radio terminal 22 is started, thecontrolling section 43 determines whether or not the reference signalhas been received. When the controlling section 43 has received thereception signal, the controlling section 43 selects an antenna gainpattern 71 of an antenna 70 having the highest communication qualityfrom the antenna gain patterns 71 of the antennas 70 through which thereference signal has been received and supplies an antenna switchingsignal corresponding to the selected antenna gain pattern 71 to theantenna switching and combining device 42. As the communication qualityof the antennas 70, for example, a measurement result of receptionpower, S/N, or error rate is used.

When the controlling section 43 has determined that the antenna gainpattern 71 of which those of adjacent two antennas 70 are combined beoptimum, the controlling section 43 supplies an antenna switching signalto the antenna switching and combining device 42 to, select adjacent twoantennas 70. In addition, the controlling section 43 supplies a variablephase shifter control signal to the variable phase shifter 41corresponding to the antenna gain patterns 71 of the antennas 70 to becombined based on their phase shifter adjustment patterns stored in thememory 46.

Thereafter, the controlling section 43 transmits the response signalcorresponding to the reference signal received from the radio basestation 21 through the selected antenna 70 and performs pairing betweenthe substrate 11 and the radio base station 21.

Thereafter, the controlling section 43 establishes a link with the radiobase station 21 through the antenna 70 through which pairing has beensuccessfully performed and performs radio communication between theradio base station 21 and the radio terminal 22 through the establishedlink. If a communication state of the selected antenna is deteriorating,the controlling section 43 switches from the deteriorating antenna 70 toanother antenna 70 and performs radio communication through the antenna70.

When adjacent two antennas 70 are selected, the phases of the twoantennas 70 are changed by the variable phase shifter 41. The phases ofthe antennas 70 are adjusted based on a variable phase shifter controlsignal supplied from the controlling section 43. Radio signals receivedby the adjacent antennas 70 are combined by the antenna switching andcombining device 42 and then the combined signal is supplied to thereception circuit section 45.

With reference to FIG. 10, the structure of the radio terminal 22 hasbeen described. The structure of the radio terminal 22 can be applied tothe radio base station 21.

In the second embodiment, by combining antenna gain patterns of adjacentantennas 70, a new antenna gain pattern different from those of theantennas 70 can be obtained. In other words, since the number of antennagain patterns that is larger than the number of antennas can beobtained, the number of antennas mounted on the antenna apparatus can bedecreased. Thus, the antenna apparatus can be more downsized.

Although the first and second embodiments of the present invention weredescribed, it should be understood by those skilled in the art thatvarious modifications, combinations, sub-combinations and alternationsmay occur depending on design requirements and other factors insofar asthey are within the scope of the appended claims or the equivalentsthereof. For example, diversity control according to embodiments of thepresent invention may be applied to wireless LAN systems other thanLocationFree.

The number of antennas of the antenna apparatus of the foregoing firstand second embodiments are just exemplary. In other words, the number ofantennas disposed on the antenna apparatus is not limited to a specificnumber.

1. An antenna apparatus, comprising: a first antenna, a second antenna,and a third antenna which have different directivity directions eachother and which are switched for a desired directivity direction,wherein the first antenna is disposed on a substrate which is inparallel therewith, wherein the second antenna is disposed on oneprincipal surface of the substrate which is nearly perpendicularthereto, wherein the third antenna is disposed on the other principalsurface of the substrate which is nearly perpendicular thereto.
 2. Theantenna apparatus as set forth in claim 1, wherein by combining gainpatterns of adjacent two antennas of the first antenna, the secondantenna, and the third antenna, a fourth antenna pattern is obtained ina direction different from a first antenna gain pattern obtained fromthe first antenna, a second antenna gain pattern obtained from thesecond antenna, and a third antenna gain pattern obtained from the thirdantenna.
 3. The antenna apparatus as set forth in claim 1, wherein aconnector socket is mounted on the substrate, wherein pin headers aremounted on the second antenna and the third antenna, and wherein byfitting the pin headers to the connector socket, the second antenna andthe third antenna are nearly perpendicularly connected to the substrate.4. The antenna apparatus as set forth in claim 3, wherein the pin headerhas at least three pins and the at least three pins are fit to theconnector socket.